Field of the Invention
The present invention relates to a light fixture and, more particularly, to a light fixture capable of selectively varying the light intensity in response to variations in power and/or data.
Description of the Related Art
The use of dimmers to vary the intensity of light is common in light fixtures used in homes and commercial facilities and for other applications, such as stage lighting. Dimming of incandescent lights is typically accomplished by varying the power/voltage delivered to the lamp, through a process known as “phase-cut” or rheostat dimming, by sliding a switch or turning a knob. However, dimming of light emitting diodes (LEDs), which are being used in place of incandescent lights in many applications due to their greater efficiency and decreased operating costs, as well as some other light technologies, cannot be accomplished by varying the power/voltage in the same manner as incandescent lights. Because LEDs operate at significantly lower powers/voltages than incandescent lights, conventional dimmers (i.e., “triac dimmers” or “legacy dimmers”) designed for incandescent lights do not function properly with LEDs, resulting in a significantly smaller dimming range. Instead, the intensity of LED fixtures is typically varied by sending data control signals to the LED drivers.
Light fixtures used in theaters, studios, auditoriums and other facilities for stage and studio lighting and other similar purposes, have traditionally used incandescent light sources and, therefore, the facilities have been built with power/voltage dimming systems. The inability of LED light fixtures to function properly with these legacy power dimming systems has been an impediment to the adoption of LED light fixtures in these existing facilities that have already invested significant resources to build the current infrastructure. These facilities and installations using incandescent lights and legacy power dimmers cannot simply add dimmable LED fixtures into the existing power infrastructure without also making substantial infrastructure changes to power the LED fixtures, because the LED fixtures will not operate properly, as the power in the existing infrastructure is varied to dim the incandescent lights co-existing in the system. This has resulted in facilities with incandescent lights continuing to use incandescent light fixtures rather than incorporating and transitioning to more cost effective LED fixtures. It also results in facilities with incandescent lights not having access to advanced lighting fixtures, features and technologies that are only offered with LEDs.
Accordingly, there is a need in the art for a new and improved lighting fixture that is capable of varying the light intensity using traditional incandescent light power/voltage variation dimmers and/or data control signals. Any such fixture should be capable of consistently varying the light intensity throughout the full dimming range regardless of whether the dimming is being driven by power/voltage variation or data control signals.
U.S. Patent Application Publication No. 2009/0184662 to Given et al., discloses dimming signal generation circuits used for differing types of power dimming signals, including dimming directly from a phase cut input AC line, DC voltage level dimming (e.g., 0-10V DC dimming) and/or pulse-width modulated (PWM) dimming. Additionally, the dimming level detection circuit of Given et al., may be configurable by component selection and/or by connection to different input connectors associated with at least two different types of power dimming signals.
Additionally, U.S. Pat. No. 8,643,304 to Hamel et al., discloses a dimming protocol detection for a light fixture for detecting a dimming protocol from a plurality of dimming protocols, such as a 0-10 volt lighting control, digital addressable lighting interface (DALI), digital multiplex (DMX512) lighting interface, a remote device management (RDM) interface, or a combination thereof. Additionally, Hamel et al., discloses a light fixture including a light dimming control module configured to control the plurality of lights based on the detected dimming protocol.
These prior art systems are structured for use with either power dimming signals or dimming control protocols. Neither discloses or suggests the ability to be used with both conventional power dimmers (i.e., phase cut dimmers) and data control dimmers, nor do they disclose or suggest the need for an LED light fixture that can be installed in legacy power dimming systems, and can operate in response to both traditional power dimming signals and digital data control signals, so that these existing facilities can begin to adopt LED light fixtures, and benefit from the advanced features, functionality and performance offered by LED light fixtures, without the need for significant investment in new infrastructure.
Accordingly, what is needed is a light fixture capable of automatically sensing the presence of dimming signals from power/voltage dimmers (i.e., phase-cut dimmers) and data control protocol dimmers and determining a priority for applying a dimming signal. For example, a light fixture is needed that can be used with legacy power dimmers and digital data control protocol dimmers such as, among others, digital multiplexing (DMX512 or DMX), ACN, ArtNet, KlingNet, Dali or any other data control protocol now known or later developed.